1. Brew strong coffee or espresso and let it cool. Mix in rum or bourbon, if using.

2. In a chilled bowl, whip the heavy cream with 1 tsp vanilla until stiff peaks form.

3. In another bowl, blend mascarpone with eggnog until smooth. For custard style, whisk egg yolks and sugar over a double boiler until pale, then combine with mascarpone.

4. Gently fold the whipped cream into the mascarpone mixture until fully incorporated.

5. Quickly dip ladyfingers one by one into the coffee mixture, then line the bottom of an 8×8 or 9×9 dish.

6. Spread half of the cream mixture over the dipped ladyfingers and smooth the surface.

7. Repeat the layers: dip more ladyfingers, then top with remaining cream.

8. Cover and refrigerate for at least 6 hours or overnight.

9. Dust with cocoa powder before serving. Add a pinch of nutmeg or cinnamon for extra flavor.